The invention relates to a blanker for reducing interference between clustered radio transmitters and receivers. More particularly, it relates to blankers which are programmable so that the nature of the blanking pulses supplied can be easily changed. Further, the present invention relates to blanker systems that are adaptive in their ability to accept various input pulses from the transmitters and to generate output signals of various voltages.
Hard-wired logic blanker systems have been used for many years in applications where a plurality of transmitters and receivers are in close proximity, or operate on closely spaced frequencies. Suitably timed blanking pulses of the proper amplitude must be supplied to the receivers so as to overcome the effects of interference from the transmitters, when the transmitters are in operation.
In critical applications, such as military aircraft, a blanker system must be of extremely high reliability. If it is necessary to change the components in the system or to rewire the logic to change the performance in light of a new environment or new sets of requirements, the equipment must be requalified. This is a time consuming and expensive process.
More recently, programmable interference blanking systems have been proposed. In such systems, information concerning the exact configuration required can be fed into a microprocessor which then provides outputs to control the blanking system. Since the data supplied to the microprocessor can be changed, the manner in which the blanking system performs can also be modified.
In these proposed blankers, input signals are generally sent to a switching matrix to provide signals at appropriate outputs in response to given inputs. The signals of the outputs are then processed so as to change their timing. The resulting output pulses are suitably buffered and applied to the appropriate receivers.
This approach generally does not provide the amount of flexibility required. For example, it may be desirable to have an output supplied when any one of four inputs is activated. However, the four inputs may occur at different times. This approach is not satisfactory when the output pulse must occur at a time not dependent upon which input has caused it to occur.
The above-mentioned approach also does not permit control of the output pulses in a flexible and programmable manner in response to a series of logic control pulses. For example, when many electronic systems may be installed in an aircraft, the requirements for blanking pulses will depend upon which systems are, in fact, installed and operating. Further, there may be several modes of operation for some of the systems, and it may be desirable to change the precise nature of the blanking pulses to optimize overall system performance in accordance with which systems are operational, and the modes in which they are operating, at a given time. Proposed blanking systems do not generally provide such enhanced flexibility.
While it is desirable to be able to reprogram a blanker system without "opening the box" to avoid any sort of requalification requirements, if the nature of the input signals is drastically changed, it may be necessary to change components within the system. Proposed blanker systems have not generally dealt adequately with the question of quickly and easily changing such components in a manner likely to avoid most of the requalification requirements.